The present invention relates to a heat exchanger comprised of a plurality of parallel heat exchanger tubes having a flow cross-section for the flow of a medium partaking in the heat exchange which flow cross-section has a great width compared to its height, whereby at each of the two plane sides of the heat exchanger tubes ribs are attached that are formed from a rib band which is meander-shaped.
A heat exchanger of this kind is known from German Offenlegungsschrift 40 39 293. The heat exchanger tubes used in this embodiment are comprised of two half shells to which are fastened ribs with a suitable device. Subsequently, the two half shells are connected to one another so that heat exchanger tubes with a cross-section of an elongate oval result. The ribs in this known heat exchanger are formed from a rib band which, before fastening to the plane surfaces of the individual heat exchanger tube, is bent multiple times to provide a meander-shape for the required rib design. Subsequently, the thus formed and shaped rib band is connected to the respective plane sides of the heat exchangers tubes.
In one of the embodiments of the known heat exchanger it is suggested to provide the ribs, manufactured from an endless rib band and forming a continuous channel over the length of the plane sides, with stamped areas in the form of lateral projections. In this manner, the medium flowing within the channels formed by the ribs is subjected to an increased turbulence which is favorable for increasing the heat exchange effect.
However, it is disadvantageous with the known heat exchanger of the aforementioned kind that the channels formed by the ribs have a relatively high soiling tendency. Due to the stamped areas in the form of individual lateral projections, this soiling tendency increases even more so that especially at these locations soil particles are easily deposited which, with continuous use of the heat exchanger, can result in the complete closure of the respective channel. This results in an undesirable local decrease of the heat exchange capacity of the heat exchanger.
It is therefore an object of the present invention to improve the known heat exchanger such that the effect of possibly present contamination on the heat exchange capacity of the heat exchanger is reduced.